If you do not receive a response to a ping, or if the response is seriously delayed, you might like to take this as a warning. But who wants to ping all day? You need a ping-based monitoring utility like Smokeping.

Don’t look now, but your mailbox is full of junk, and a snooper is live on a distant server, reading your opinions of your boss. Remember when email used to be easy? To restore some sanity to your correspondence, you’ll need the right tools.

Even if you do not have a mail server of your own, SpamAssassin can help you filter out unsolicited junk mail. This article describes how SpamAssassin collaborates with Evolution and KMail. Thunderbird, on the other hand, has its own simple spam-detection feature.